To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

7a⁶ - 8a⁶ = -1a⁶

The volume of a cube is height x length x width:

v = h x l x w
v = 6 x 6 x 3
v = 108

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 27 as well and sum (Inside, Outside) to equal -12. For this problem, those two numbers are -9 and -3. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² - 12y + 27
y² + (-9 - 3)y + (-9 x -3)
(y - 9)(y - 3)

To solve this equation, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

6c(c - y)
6(6)(6 + 8)
6(6)(14)
(36)(14)
504

An acute angle measures less than 90°, a right angle measures 90°, and an obtuse angle measures more than 90°.